Evidence for the laryngeal source of ultrasonic and audible cries of rodents

The audible cries of three species of young myomorph rodents were found to be emitted through the nose and the mouth, buccal and nasal cavity resonances being involved in the production of the formant structures of the emitted cries. Ultrasonic cries were found to be emitted mainly through the mouth, with no evidence for the involvement of cavity resonances. Nerve sectioning experiments on adult and young rats implicated the larynx as the source of both their audible and their ultrasonic cries. However, consideration of the considerable differences in physical structure between the typically "vocal" audible cries and the ultrasonic cries, as well as other differences noted in the experimental conditions here and elsewhere, leads to the conclusion that the rodent larynx may operate in two quite different sound production modes.     

Application of negative expiratory pressure during expiration and activity of genioglossus in humans

The application of negative expiratory pressure(NEP) at end expiration has been shown to cause reflex-mediatedactivation of the genioglossus muscle in awake humans. To test whethera reflex contraction of pharyngeal dilator muscles also occurs in response to NEP applied in early expiration, the effect on genioglossus muscle reflex activity of NEP pulses of 500 ms, given 0.2 s after theonset of expiration and during the end-expiratory pause, was assessedin 10 normal awake subjects at rest. The raw and integrated surfaceelectromyogram of the genioglossus (EMGgg) was recorded with airflowand mouth pressure under control conditions and with NEP ranging from3 to 10 cmH₂O.Intraoral EMGgg was also recorded under the same experimentalconditions in two subjects. The application of NEP at theend-expiratory pause elicited a consistent reflex response of EMGgg inseven subjects with a mean latency of 68 ± 5 ms. In contrast, whenNEP was applied at the onset of expiration, EMGgg reflex activity wasinvariably observed in only one subject. No relationship was foundbetween steady increase or abrupt fall in expiratory flow and thepresence or the absence of a reflex activity of genioglossus duringsudden application of NEP at the beginning of expiration. Our resultsshow that a reflex activity of genioglossus is elicited much morecommonly during application of NEP at the end rather than at the onsetof expiration. These findings also suggest that when NEP is applied inearly expiration to detect intrathoracic flow limitation the absence ofupper airways narrowing does not imply the occurrence of areflex-mediated activation of genioglossus and vice versa.

     

Sound radiation patterns in the frequency domain of cries from a vespertilionid bat

Summary Ultrasonic cries from an immobilized vespertilionid batMyotis daubentoni, were recorded simultaneously in front of the bat (on-axis), and at various off-axis angles. The differences between the on-axis and off-axis spectra were computed and related to the theory of directional emission from a baffled rigid-piston radiator. This theory implies zero radiation at a specific frequency for a given piston diameter and off-axis angle (Fig. 1). The bat's difference spectra showed notches of ca. 25 dB with properties as the zeros of the piston theory (Fig. 7). The structure of off-axis cries was found to be qualitatively predictable from the on-axis cries, using the piston theory (Fig. 4). The difference spectra had a complex, oscillatory fine-structure that could not be accounted for by the basic piston theory.Supported by grants from the Danish Science Research Council for Natural Sciences     

Prolactin responses to infant cues in men and women: effects of parental experience and recent infant contact

We used a longitudinal design to test whether parental experience differentially affects the development of prolactin responses to infant cues in men and women. Couples provided two blood samples at three tests, one test just before their babies were born, and two tests during the early postnatal period (n=21). Nine couples repeated the tests near the birth of their second babies. In the 30 min between the two samples, couples listened to recorded infant cries at the prenatal test and held their baby (fathers) or a doll (mothers) at the postnatal tests. Blood samples were analyzed for prolactin concentrations. Prolactin values were then related to sex and parity differences as well as to questionnaire data concerning emotional responses to infant cries and previous infant contact. We found that (1) prior to the birth of both the first and second babies, women's prolactin concentrations increased after exposure to infant stimuli, whereas men's prolactin concentrations decreased; postnatal sex differences varied with parity; (2) women's prolactin reactivity did not change significantly with parental experience; (3) the same men's prolactin concentrations decreased after holding their first newborns but increased after holding their second newborns; this change was not gradual or permanent; (4) men reporting concern after hearing recorded infant cries showed a different postnatal pattern of prolactin change after holding their babies than men not reporting concern; and (5) men who had little contact with their babies just prior to testing had a more positive prolactin response than men who had recently held their babies for longer periods. Although parental experience appears to affect men's prolactin responses, differences in reactivity were also related to patterns of recent infant contact and individual differences in responses to infant cues.     

Viscoelasticity of the trachea and its effects on flow limitation.

To test the hypothesis that peak expiratory flow is determined by the wave-speed-limiting mechanism, we studied the time dependency of the trachea and its effects on flow limitation. For this purpose, we assessed the relationship between transmural pressure and cross-sectional area [the tube law (TL)] of six excised human tracheae under controlled conditions of static (no flow) and forced expiratory flow. We found that TLs of isolated human tracheae followed quite well the mathematical representation proposed by Shapiro (Shapiro AH. J Biomech Eng 99: 126-147, 1977) for elastic tubes. Furthermore, we found that the TL measured at the onset of forced expiratory flow was significantly stiffer than the static TL. As a result, the stiffer TL measured at the onset of forced expiratory flow predicted theoretical maximal expiratory flows far greater than those predicted by the more compliant static TL, which in all cases studied failed to explain peak expiratory flows measured at the onset of forced expiration. We conclude that the observed viscoelasticity of the tracheal walls can account for the measured differences between maximal and "supramaximal" expiratory flows seen at the onset of forced expiration.     

The interaction between breathing and swallowing in healthy individuals

In this article, we aimed at investigating the interaction between breathing and swallowing patterns in normal subjects. Ten healthy volunteers were included in the study. Diaphragm EMG activity was recorded by a needle electrode inserted into the 7th or 8th intercostal space. Swallowing was monitored by submental EMG activity, and laryngeal vertical movement was recorded by using a movement sensor. A single voluntary swallow was initiated during either the inspiration or expiration phases of respiration, and changes in EMG activity were evaluated. When a swallow coincided with either inspiration or expiration, the duration of the respiratory phase was prolonged. Normal subjects were able to voluntarily swallow during inspiration. During the inspiration phase with swallowing, diaphragmatic activity did not ceased and during the expiration phase with swallowing, there was a muscle activity in the diaphragm muscle.     

Rate effects on timing, key velocity, and finger kinematics in piano performance

We examined the effect of rate on finger kinematics in goal-directed actions of pianists. In addition, we evaluated whether movement kinematics can be treated as an indicator of personal identity. Pianists' finger movements were recorded with a motion capture system while they performed melodies from memory at different rates. Pianists' peak finger heights above the keys preceding keystrokes increased as tempo increased, and were attained about one tone before keypress. These rate effects were not simply due to a strategy to increase key velocity (associated with tone intensity) of the corresponding keystroke. Greater finger heights may compensate via greater tactile feedback for a speed-accuracy tradeoff that underlies the tendency toward larger temporal variability at faster tempi. This would allow pianists to maintain high temporal accuracy when playing at fast rates. In addition, finger velocity and accelerations as pianists' fingers approached keys were sufficiently unique to allow pianists' identification with a neural-network classifier. Classification success was higher in pianists with more extensive musical training. Pianists' movement "signatures" may reflect unique goal-directed movement kinematic patterns, leading to individualistic sound.     

Plurisegmental neurones of the cricket Gryllus campestris L. that discharge in the rhythm of its own song

Male crickets (Gryllus campestris L.) mounted so that their wings and abdomen could move freely were induced to stridulate by brain lesion. During the song the activity of single neurones was recorded extracellularly in a cervical connective. Nine distinct spike patterns were observed. Patterns I and II tend to copy the chirp as a whole rather than the onset of the syllables (the recorded potentials of the wing-opener muscle M99 marked the syllable onset). The other patterns reflect the syllabic structure. Each, in its own way, marks the various syllables with different numbers of spikes. The delay of the spike response is different for each pattern. Some patterns, but not others, also reflect the beginning or end of the song, or the abdominal expiratory activity. One neurone also responds in correlation with muscle discharges typical of the courtship song. In some of the patterns it is evident that there is a stronger correlation with the closer muscle (M90) discharge than with the opener muscle discharge. Activation by auditory self-stimulation by way of the tympanal organs can be ruled out for all patterns. It is possible that patterns I–V are induced by afferent activity coupled to the wing movement. Patterns VI–VIII are probably copies of motor signals ascending from the thoracic song-pattern generators to the head ganglia. It is evident that the head ganglia have detailed information as to the motor output for stridulation and abdominal expiration.     

Effects of auditory stimulus timing in the respiratory cycle on the evoked cardiac response in man at rest

The present experiments were carried out in 21 healthy adults to study the effects of auditory stimulus timing within the respiratory cycle on evoked cardiac response. The stimulus (80 dB white noise) was started by the first and finished by the second R-wave after change in respiratory phase, and presented in different series in either early inspiration or early expiration. The spirogram and eight sequential interbeat intervals (IBI) after respiratory phase change were recorded. The mean of IBI and standard deviation (SD) were calculated separately for each IBI of 20 trials for each subject, during both the prestimulus and poststimulus phases. The stimulus effects were expressed as changes from prestimulus conditions, in terms of delta IBI and delta SD. The mean of each of the eight IBI and its SD were found to vary consistently in the same direction, i.e., SD increased with increasing mean IBI. Stimulation during early inspiration did not produce any effect during this respiratory phase. It was not before the beginning of the following expiration that a significant deceleration was evoked, which was associated with an enhanced delta SD, whereas stimulation during early expiration promptly evoked a biphasic cardiac response of the deceleration - acceleration pattern and an increase and decrease in delta SD, respectively. While SD was found to be a function of age, no such finding was obtained for delta IBI and delta SD. These results are discussed in terms of the "vagal gating" hypothesis.     

Effects of motherhood on physiological and subjective responses to infant cries in teenage mothers: a comparison with non-mothers and adult mothers

The present study was designed to determine whether becoming a mother during the adolescent period changes maternal responsiveness or maternal motivation, assessed through hormonal, autonomic, and hedonic responses to recorded infant cries and interactions with their babies. Fifty-six teen mothers were compared to 58 teen non-mothers and 49 adult mothers. Teen mothers reported more sympathy and alertness in response to recorded infant cries compared to non -mother teens; however, among the teen women there were no differences between mothers and non-mothers in heart rate and cortisol responses to infant cries. In contrast, in comparison to adult mothers, teen mothers reported the same levels of sympathy and alertness to infant cries; however, adult mothers showed an 'alerted' pattern of heart rate and cortisol response to infant cries not seen in the teen mother group. Inclusion of the covariate, fathers' employment classification as an index of SES or time of testing and cortisol sampling did not affect this pattern of results. Taken together, these results show that where self-report is used as a measure of maternal responsiveness, teen mothers are no different in responsiveness than adult mothers; however, where physiological and interactional measures of responsiveness are considered, teen mothers are less likely to show heightened or selective responses to infant cries or respond 'attentively' to the infant.     

Synchronization of respiratory frequency by somatic afferent stimulation.

In cats anesthetized with chloralose-urethan, vagotomized, paralyzed, and artifically ventilated, superficial radial (cutaneous) and hamstring (muscle) nerve afferents were stimulated while phrenic nerve electrical activity was recorded. The results obtained with both types of nerves were similar. Stimulation in mid and late expiration advanced the onset of the next inspiration, shortening its duration. Stimulation in early inspiration advanced, while that in late inspiration delayed, the onset of the next expiration. These effects were often accompanied by changes in phrenic motoneuron firing patterns (earlier recruitment, increased discharge frequency, increased slope of integrated phrenic neurogram). Repetitive somatic afferent stimulation produced sustained increases in respiratory frequency in all cats and in half of them entrainment of respiratory frequency to the frequency of stimulation occurred at ratios such as 4:3, 4:5, 1:2, 1:3, 1:4, and 1:7. The lowest stimulus intensity required for evoking these phase shifts was between 5 and 10T (threshold of most excitable fibers) for muscle afferents and between 1 and 2T for cutaneous afferents. These results demonstrate the existence of a reflex mechanism capable of locking respiratory frequency to that of a periodic somatic afferent input. They also provide an experimental basis for the hypothesis that reflexes are resposible for the observed locking between step or pedal frequency and respiratory rate during exercise in man.     

Coordination of swallowing and respiration in unconscious subjects

We investigated the coordination of swallowing and breathing in 11 unconscious patients with an endotracheal tube in place during the recovery period from general anesthesia. Swallows occurred during both the inspiratory and expiratory phases with no preponderant occurrence during either phase. When a swallow occurred during inspiration, the inspiration was interrupted immediately and was followed by expiration, but the durations of both inspiration and expiration were progressively increased as the time from the onset of inspiration to the onset of swallowing was progressively delayed. A swallow coinciding with the expiratory phase progressively prolonged the duration of the expiration that had been interrupted as the timing of swallowing was progressively delayed. Repeated swallows invariably and in a predictable manner caused changes in the breathing pattern. Thus when the frequency of regularly repeated swallows was relatively high, the breathing pattern was characterized by regular, shallow, and rapid breaths. When the frequency of regularly repeated swallows was relatively low, the breathing pattern was characterized by regular, deep, and slow breaths. When the frequency of repeated swallows was irregular, the breathing patterns were characterized by inconsistent changes in tidal volume and respiratory frequency. Our results indicate that, in unconscious subjects, some mechanisms integrating respiration and swallowing are operative and responsible for changes in breathing patterns during swallowing.     

Body temperature patterns before, during, and after semi-natural hibernation in the European ground squirrel

Ground squirrels undergo extreme body temperature fluctuations during hibernation. The effect of low body temperatures on the mammalian circadian system is still under debate. Using implanted temperature loggers, we recorded body temperature patterns in European ground squirrels kept in an enclosure under natural conditions. Although hibernation onset was delayed, hibernation end corresponded closely to that measured in a field population. Circadian body temperature fluctuations were not detected during deep torpor, but indications of circadian timing of arousal episodes at higher temperatures were found at the beginning and end of hibernation. One male exhibited synchronised arousals to a relatively constant phase of the day throughout hibernation. All animals first entered torpor in the afternoon. Daily body temperature fluctuations were decreased or distorted during the first days after hibernation. We hypothesise that hibernation may affect the circadian system by either decreasing the expression of the circadian oscillator, or by decreasing the amplitude of the circadian oscillator itself. possibly due to gradual, temperature dependent, internal desynchronisation. The latter mechanism may be beneficial because it might facilitate post-hibernation re-entrainment rates.     

Ultrasound and aggressive behaviour in rats and other small mammals

Aggressive behaviour has been observed in rats, Rattus norvegicus, and fourteen other species of small mammals. Ultrasounds were detected during aggressive behaviour in at least seven of these species, and in rats two distinct types of signal were recorded. Short ultrasounds of 3 to 65 ms duration and at frequencies of about 50 kHz were produced in aggressive situations, while long pulses up to 3400 ms duration and at about 25 kHz appeared to be synchronous with the long exhalations of submissive rats. Aggressive behaviour was reduced in encounters where long pulses were emitted. The physical characteristics of the ultrasounds produced by the different species are described and the importance of these signals in the establishment and maintenance of social relationships in small mammals is discussed.     

Ventrolateral medullary respiratory network participation in the expiration reflex in the cat.

The expiration reflex is a distinct airway defensive response characterized by a brief, intense expiratory effort and coordinated adduction and abduction of the laryngeal folds. This study addressed the hypothesis that the ventrolateral medullary respiratory network participates in the reflex. Extracellular neuron activity was recorded with microelectrode arrays in decerebrated, neuromuscular-blocked, ventilated cats. In 32 recordings (17 cats), 232 neurons were monitored in the rostral (including B?tzinger and pre-B?tzinger complexes) and caudal ventral respiratory group. Neurons were classified by firing pattern, evaluated for spinal projections, functional associations with recurrent laryngeal and lumbar nerves, and firing rate changes during brief, large increases in lumbar motor nerve discharge (fictive expiration reflex, FER) elicited during mechanical stimulation of the vocal folds. Two hundred eight neurons were respiratory modulated, and 24 were nonrespiratory; 104 of the respiratory and 6 of the nonrespiratory-modulated neurons had altered peak firing rates during the FER. Increased firing rates of bulbospinal neurons and expiratory laryngeal premotor and motoneurons during the expiratory burst of FER were accompanied by changes in the firing patterns of putative propriobulbar neurons proposed to participate in the eupneic respiratory network. The results support the hypothesis that elements of the rostral and caudal ventral respiratory groups participate in generating and shaping the motor output of the FER. A model is proposed for the participation of the respiratory network in the expiration reflex.     

Sustained potential shifts,alterations in acoustic evoked potential amplitude and bradycardiac responses to the onset of illumination in the goldfish (Carassius auratus)

Sustained potential shift's (SPSs) and changes in acoustic evoked potential (AEP) amplitudes were recorded from medullary and mid-brain regions in restrained goldfish (Carassius auratus) in response to the onset of illumination against a sensory background restricted to repetitive (1/s) acoustic stimulation. At the tectal surface, a long duration negative SPS, significant 5–10 s after the onset of illumination, was recorded with a maximum negativity of ca. 145 V. Changes in acoustic responsiveness were also most apparent in the mid-brain where attenuations in AEP amplitude of ca. 15% were recorded.In general, AEPs exhibited attenuated amplitudes in response to the onset of illumination, perhaps reflecting attentional rather than arousal processes, arousal generally being associated with heightened sensory responsiveness. Changes in the amplitude of the medullary AEPs were directly related to the magnitude of bradycardiac responses such that lesser attenuations of the medullary AEP were associated with greater magnitude bradycardiac responses, suggesting a possible interaction of attentional and arousal processes.In response to repeated onset of illumination, SPSs tended towards increasing positivity (increasing in positivity at the medullary surface; decreasing in negativity at the tectal surface). The attenuation of AEPs recorded from the medulla and mid-brain habituated in response to stimulus repetition.Changes in amplitude of AEPs (AEP) recorded from the telencephalon and the torus semicircularis region of the mid-brain were correlated with locally recorded SPSs. At the telencephalon, this correlation was inverse; enhanced AEP amplitudes being associated with SPS negativity, attenuated AEP amplitudes with SPS positivity. In the torus semicircularis, experiential changes in SPS and AEP were directly correlated. As the SPS is considered to reflect glial redistribution of [K⁺]_e (Roitbak 1983), glia may contribute to changes in measures of sensory responsivity, such as the AEP, during changes in behavioural state.Abbreviations AEP Acoustic Evoked Potential - AEP Event-related change in amplitude of AEP following onset of illumination - SPS Sustained Potential Shift - [K⁺]_e Extracellular concentration of K⁺     

Regional brain responses in nulliparous women to emotional infant stimuli

Infant cries and facial expressions influence social interactions and elicit caretaking behaviors from adults. Recent neuroimaging studies suggest that neural responses to infant stimuli involve brain regions that process rewards. However, these studies have yet to investigate individual differences in tendencies to engage or withdraw from motivationally relevant stimuli. To investigate this, we used event-related fMRI to scan 17 nulliparous women. Participants were presented with novel infant cries of two distress levels (low and high) and unknown infant faces of varying affect (happy, sad, and neutral) in a randomized, counter-balanced order. Brain activation was subsequently correlated with scores on the Behavioral Inhibition System/Behavioral Activation System scale. Infant cries activated bilateral superior and middle temporal gyri (STG and MTG) and precentral and postcentral gyri. Activation was greater in bilateral temporal cortices for low- relative to high-distress cries. Happy relative to neutral faces activated the ventral striatum, caudate, ventromedial prefrontal, and orbitofrontal cortices. Sad versus neutral faces activated the precuneus, cuneus, and posterior cingulate cortex, and behavioral activation drive correlated with occipital cortical activations in this contrast. Behavioral inhibition correlated with activation in the right STG for high- and low-distress cries relative to pink noise. Behavioral drive correlated inversely with putamen, caudate, and thalamic activations for the comparison of high-distress cries to pink noise. Reward-responsiveness correlated with activation in the left precentral gyrus during the perception of low-distress cries relative to pink noise. Our findings indicate that infant cry stimuli elicit activations in areas implicated in auditory processing and social cognition. Happy infant faces may be encoded as rewarding, whereas sad faces activate regions associated with empathic processing. Differences in motivational tendencies may modulate neural responses to infant cues.     

The acoustic space of pain: cries as indicators of distress recovering dynamics in pre-verbal infants

Crying is a vital built-in survival mechanism for the human baby. Yet both the information carried by cries and the factors driving the perception and reaction of adult listeners remain under-investigated. Here, we contrasted the relevance of psycho-acoustic vs. acoustic evaluation for the assessment of distress levels in babies’ cries recorded during baths and during an immunization event. Parents were asked to rate the level of distress experienced by babies from listening to their cries attributed lower pain ratings to mild discomfort (bath) than to distress (vaccination) cries but failed to discriminate between different putative levels of pain experienced during different vaccination sequences. In contrast, vocal ‘roughness’, a composite acoustic factor characterizing the level of aperiodicity of the cries, not only differed between mild discomfort and distress cries but also between the levels of pain experienced during the different vaccination sequences. These observations suggest that acoustic analyses are more powerful than psycho-acoustic evaluations for discriminating distress levels in babies’ cries, and opens the way for the design of a tool based on the acoustics of cries for assessing and monitoring pain levels in pre-verbal infants.     

Preterm birth is associated with an increased fundamental frequency of spontaneous crying in human infants at term-equivalent age

Human infant crying has been researched as a non-invasive tool for assessing neurophysiological states at an early developmental stage. Little is known about the acoustic features of spontaneous cries in preterm infants, although their pain-induced cries are at a higher fundamental frequency (F₀) before term-equivalent age. In this study, we investigated the effects of gestational age, body size at recording and intrauterine growth retardation (IUGR) on the F₀ of spontaneous cries in healthy preterm and full-term infants at term-equivalent age. We found that shorter gestational age was significantly associated with higher F₀, although neither smaller body size at recording nor IUGR was related to increased F₀ in preterm infants. These findings suggest that the increased F₀ of spontaneous cries is not caused by their smaller body size, but instead might be caused by more complicated neurophysiological states owing to their different intrauterine and extrauterine experiences.     

Respiratory neuronal activity during apnea and other breathing patterns induced by laryngeal stimulation

Respiration cycles through three distinct phases (inspiration, postinspiration, and expiration) each having corresponding medullary cells that are excited during one phase and inhibited during the other two. Laryngeal stimulation is known to induce apnea in newborn animals, but the cellular mechanisms underlying this effect are not known. Intracellular recording of ventral respiratory group neurons was accomplished in intact anesthetized, paralyzed, and mechanically ventilated piglets. Apnea was induced by insufflation of the larynx with ammonia-saturated air, smoke, or water. Laryngeal insufflation induced phrenic nerve apnea, stimulation of postinspiratory neurons, and stable membrane potentials in inspiratory and expiratory cells consistent with postinspiratory inhibition. Usually the membrane potential of each neuronal type cycled through an expiratory level before onset of the first recovery breath. Variants of the apnea response, probably reflecting the aspiration reflex or sniffing, sneezing, coughing, and swallowing, were also observed. These latter patterns showed oscillation between inspiration and postinspiration without an apparent intervening stage II expiratory phase. However, stage II expiratory activity always preceded onset of the first ramp inspiration after such a pattern. These findings suggest that activation of postinspiratory mechanisms causes profound alterations in the respiratory pattern and that stage II expiration importantly modulates recovery of ramp inspiratory activity. The mechanism of this latter effect may be inhibition of early inspiratory neurons with consequent postinhibitory rebound.